1. Field of the Invention
This invention relates to inhibitors of one or more proteins in the Wnt pathway, including inhibitors of one or more Wnt proteins, and compositions comprising the same. More particularly, it concerns the use of a 1H-pyrazolo[3,4-b]pyridine compound or salts or analogs thereof, in the treatment of disorders characterized by the activation of Wnt pathway signaling (e.g., cancer, abnormal cellular proliferation, angiogenesis, Alzheimer's disease, lung disease, osteoarthritis and idiopathic pulmonary fibrosis), the modulation of cellular events mediated by Wnt pathway signaling, as well as genetic diseases and neurological conditions/disorders/diseases. Also provided are methods for treating Wnt-related disease states.
2. Description of the Related Art
Pattern formation is the activity by which embryonic cells form ordered spatial arrangements of differentiated tissues. Speculation on the mechanisms underlying these patterning effects usually centers on the secretion of a signaling molecule that elicits an appropriate response from the tissues being patterned. More recent work aimed at the identification of such signaling molecules implicates secreted proteins encoded by individual members of a small number of gene families.
A longstanding idea in cancer biology is that cancers arise and grow due to the formation of cancer stem cells, which may constitute only a minority of the cells within a tumor but are nevertheless critical for its propagation. Stem cells are appealing as the cell of origin for cancer because of their pre-existing capacity for self-renewal and for unlimited replication. In addition, stem cells are relatively long-lived in comparison to other cells within tissues, providing a greater opportunity to accumulate the multiple additional mutations that may be required to increase the rate of cell proliferation and produce clinically significant cancers. Of particular recent interest in the origin of cancer is the observation that the Wnt signaling pathway, which has been implicated in stem cell self-renewal in normal tissues, upon continuous activation has also been associated with the initiation and growth of many types of cancer. This pathway thus provides a potential link between the normal self-renewal of stem cells and the aberrantly regulated proliferation of cancer stem cells.
The Wnt growth factor family includes more than 10 genes identified in the mouse and at least 19 genes identified in the human. Members of the Wnt family of signaling molecules mediate many important short- and long-range patterning processes during invertebrate and vertebrate development. The Wnt signaling pathway is known for its important role in the inductive interactions that regulate growth and differentiation, and plays important roles in the homeostatic maintenance of post-embryonic tissue integrity. Wnt stabilizes cytoplasmic β-catenin, which stimulates the expression of genes including c-myc, c jun, fra-1, and cyclin D1. In addition, misregulation of Wnt signaling can cause developmental defects and is implicated in the genesis of several human cancers. More recently, the Wnt pathway has been implicated in the maintenance of stem or progenitor cells in a growing list of adult tissues that now includes skin, blood, gut, prostate, muscle and the nervous system.
Pathological activation of the Wnt pathway is also believed to be the initial event leading to colorectal cancer in over 85% of all sporadic cases in the Western world. Activation of the Wnt pathway has also been extensively reported for hepatocellular carcinoma, breast cancer, ovarian cancer, pancreatic cancer, melanomas, mesotheliomas, lymphomas and leukemias. In addition to cancer, inhibitors of the Wnt pathway can be used for stem cell research or for the treatment of any diseases characterized by aberrant Wnt activation such as idiopathic pulmonary fibrosis (IPF), diabetic retinopathy, neovascular glaucoma, rheumatoid arthritis, psoriasis as well as mycotic and viral infections and bone and cartilage diseases. As such, it is a therapeutic target that is of great interest to the field.
Idiopathic pulmonary fibrosis (IPF) is a ravaging condition of progressive lung scarring and destruction. This is a chronic, progressive, usually fatal, lung disease characterized by excessive fibrosis which causes eventual deterioration of the lung's architecture [Nature Reviews Drug Discovery (2010), 9(2), 129-140]. Recently, the Wnt/β-catenin pathway has become implicated in the etiology of the disease [Annals of the Rheumatic Diseases (2012), 71(5), 761-767; Respiratory Research (2012), 13(3), pp. 9]. At the cellular level, it is has been shown that β-catenin is overexpressed in bronchial epithelial cells which contributes to an epithelial to mesenchymal cell transition (EMT). This results in increased presence of proliferating fibroblasts and myofibroblasts which leads to excess collagen deposition in the lungs [Respiratory Research (2012), 13(3), pp. 9]. The formation of these fibroblastic foci and increased extracellular matrix deposition are pathological hallmarks of IPF.
There are also many cases of genetic diseases due to mutations in Wnt signaling components. Examples of some of the many diseases are Alzheimer's disease [Proc. Natl. Acad. Sci. USA (2007), 104(22), 9434-9], osteoarthritis, polyposis coli [Science (1991), 253(5020), 665-669], bone density and vascular defects in the eye (osteoporosis-pseudoglioma syndrome, OPPG) [N. Engl. J. Med. (2002), 346(20), 1513-21], familial exudative vitreoretinopathy [Hum. Mutat. (2005), 26(2), 104-12], retinal angiogenesis [Nat. Genet. (2002), 32(2), 326-30], early coronary disease [Science (2007), 315(5816), 1278-82], tetra-amelia syndrome [Am. J. Hum. Genet. (2004), 74(3), 558-63], Müllerian-duct regression and virilization [Engl. J. Med. (2004), 351(8), 792-8], SERKAL syndrome [Am. J. Hum. Genet. (2008), 82(1), 39-47], diabetes mellitus type 2 [Am. J. Hum. Genet. (2004), 75(5), 832-43; N. Engl. J. Med. (2006), 355(3), 241-50], Fuhrmann syndrome [Am. J. Hum. Genet. (2006), 79(2), 402-8], Al-Awadi/Raas-Rothschild/Schinzel phocomelia syndrome [Am. J. Hum. Genet. (2006), 79(2), 402-8], odonto-onycho-dermal dysplasia [Am. J. Hum. Genet. (2007), 81(4), 821-8], obesity [Diabetologia (2006), 49(4), 678-84], split-hand/foot malformation [Hum. Mol. Genet. (2008), 17(17), 2644-53], caudal duplication syndrome [Am. J. Hum. Genet. (2006), 79(1), 155-62], tooth agenesis [Am. J. Hum. Genet. (2004), 74(5), 1043-50], Wilms tumor [Science (2007), 315(5812), 642-5], skeletal dysplasia [Nat. Genet. (2009), 41(1), 95-100], focal dermal hypoplasia [Nat. Genet. (2007), 39(7), 836-8], autosomal recessive anonychia [Nat. Genet. (2006), 38(11), 1245-7], neural tube defects [N. Engl. J. Med. (2007), 356(14), 1432-7], alpha-thalassemia (ATRX) syndrome [The Journal of Neuroscience (2008), 28(47), 12570-12580], fragile X syndrome [PLoS Genetics (2010), 6(4), e1000898], ICF syndrome, Angelman syndrome [Brain Research Bulletin (2002), 57(1), 109-119], Prader-Willi syndrome [Journal of Neuroscience (2006), 26(20), 5383-5392], Beckwith-Wiedemann Syndrome [Pediatric and Developmental Pathology (2003), 6(4), 299-306] and Rett syndrome.
Regulation of cell signaling by the Wnt signaling pathway is critical for the formation of neuronal circuits. Wnt pathway modulates in neural tissue, among other things, axon pathfinding, dendritic development, and synaptic assembly. Through different receptors, Wnt pathway activates and/or regulates diverse signaling pathways and other processes that lead to local changes on the cytoskeleton or global cellular changes involving nuclear function. Recently, a link between neuronal activity, essential for the formation and refinement of neuronal connections, and Wnt signaling has been uncovered. Indeed, neuronal activity regulates the release of various Wnt proteins and the localization of their receptors. Wnt pathway mediates synaptic structural changes induced by neuronal activity or experience. Evidence suggests that dysfunction in Wnt signaling contributes to neurological disorders [Brain Research Reviews (2000), 33(1), 1-12; Oncogene (2006) 25(57), 7545-7553; Molecular Neurodegeneration (2008), 3, 9; Neurobiology of Disease (2010), 38(2), 148-153; Journal of Neurodevelopmental Disorders (2011), 3(2), 162-174 and Cold Spring Harbor Perspectives in Biology February (2012), 4(2)].